Dr Hall-Spencer has surveyed large sections of the reefs which are located about 100km (60 miles) off shore, south of Rockall.

His voyage was part of an international project using a German research vessel and a French remote-operated vehicle called Victor that can film at depth and bring back samples to the surface.

Some animals have yet to be described by science

Dr Hall-Spencer is to describe his work at the annual British Association's Festival of Science, which this year is being held in Dublin, Ireland.

"Few people realise that we have such interesting, precious and dramatic habitats right on our doorstep," Dr Hall-Spencer said. "Some of the organisms down there have not even been described by science."

Experts have long known about corals and sponges in shallow, warm, tropical waters, and discovered deep-sea corals in the late 1800s.

Until recently, however, no-one realised just how widespread these cold coral "forests" were across the globe; many are centred along the edges of continental shelves or around seamounts.

Heavy rollers

The colourful reefs and the fish and other animals they support are extremely slow-growing and, as such, are particularly vulnerable to any disturbance - which is why marine biologists are so alarmed that the fishing industry is now targeting these areas.

Victor can bring samples back to the surface

The latest nets are armed with steel weights or heavy rollers and destroy everything in their path.

Dr Hall-Spencer has radiocarbon dated some coral samples off Ireland and found them to be 4,500 years old.

"We used the robot for seven days solid and I'd say 40% of the area had been smashed up. The coral reefs we've filmed will not recover in our lifetimes."

'Small but destructive'

Efforts are being made at United Nations level to restrict the destructive practice of bottom-trawling but the moves are being met with fierce resistance by some countries, says Dr Alex Rogers, from the British Antarctic Survey.

"In terms of these deepwater trawling fleets, it's actually a very small number of fishing vessels that are operating globally - perhaps a couple of hundred boats," he told BBC News.

"These are large, powerful vessels operated by a small number of developed nations, including from Europe.

"They're having a serious impact on some of the target species they're fishing as well as a very, very damaging impact on the seabed."

Dr Hall-Spencer's research is sponsored by the Royal Society and the Esmee Fairbairn Foundation.

HOW DEEP WATER CORALS COULD BE PROTECTED

Vessels would be fitted with black boxes that would report their positions to a national fisheries monitoring centre

Boats would be warned if they were entering restricted areas; patrol vessels and aircraft would back up the system